Wireless-telegraph transmitter.



J. G. BALSILLIE.

WIRELESS TELEGRAPH TRANSMITTER.

APPLICATION FILED SEPT. 12, 1913.

Patented May 22, 1917.

2 SHEETS-SHEET I.

Witnesses:

J. G. BALSILLIE.

WIRELESS TELEGRAPH TRANSMITTER. APPLICATION FILED SEPT-12.1913.

1 ,227,521 Patented May 22, 1917.

2 SHEETS-SHEET 2.

FIG. 5

Witnesses; Inventor.

JOEN enomm BALsILLIE, or mnnnounivnvic'ronm, AUSTRALIA.

WIRELESS-TELEGRAPH TRANSMITTER.

Specification of Letters Patent.

Patented May '22, 1917.

Application filed September 12, 1913. I Serial No.,789,568;

To all whom it may concern:

Be it known that I, JOHN GRoEMn BAL- SILLIE, a subject of the King of Great Britain' and Ireland, residing at 51 Spring street, Melbourne, in the State of Victoria, Australia, have invented certain new and useful Improvements in Wireless-Telegraph Transmitters, of which the following is a specification. I This invention relates to a wireless telegraph transmitter of the type in which the radiator is connected electrostatically to an exciting circuit as contra-distinctive from transmitters in which the radiator is con nected inductively to the exciting circuit,

and has for its object the provision of effective means for energizing theradiator by.

unidirectional impulses from an exciting circuit. means whereby the exciting circuit is caused to deliver trains of unidirectional impulses into the radiator intermittently without reaction; in an arrangement of the radiator and the exciting circuit whereby a high proportion of the energy stored in the exciting circuit maybe Temitted during periods of discharge through the radiator; and in means whereby pre-charging of the radiator is inhibited. 7 I

In the accompanying drawings Figures 1 and 2 are diagrammatic views of high efficiency transmitter circuits arranged according to this invention and including the said means for intermittently discharging 85 the exciting circuit into the radiator, and

for maintaining zero potentialin the radiator. Fig. 3 is a sectional elevation of the discharge ga'p electrodes. Fig. 4 is a diagrammatic view of a T type air wire such as 40 is preferred for a radiator. Fig. 5 is a sectional elevation of an-inducta-nce contained in the exciting circuit in series with a plurality of condensers therein. Fig. 6 is a sectional elevation of an induction valve with magnetic material core contained in the radiator in shunt with the connecting condenser. V i

The means for delivering energy into the exciting circuit from a primary source of energy do not form part of the present invention. They may consist of a generator directly connected in parallel with. the condensers in the exciting circuit provided that the generator delivers electrical energy 1 of sufficient potential to pass across the discharge gap in the exciting circuit.

- The present invention consists in Those portions of the exciting circuitwhich are traversed by the feedinghigh cuit.

In practice it is most convenient to use a primary power circult lnterposed between the generator and the charging c1rcu1t, and

to couple this primary power circuit to the charging circuit inductively through atransof 500 per second. The form of radiator is immateriahthough it is preferred to use a capacity type of antenna.

The clrcuit interposed between the ra-- 'diator andthe source of primary power functions as'a charging and as an exciting circuit, certain of its elements only being operative during the charging period. This intermediate circuit is connected to the radiator by means of a condenser common to both.' 'When the intermediate circuit functions as a charging circuit and an inductively coupled power circuit is used its operative elementsare th'e transformer secondary E, the condensers F and G, the line connections between those parts, and the tension energy function as a charging cirinductance valve B. When it functions as an exciting circuit its operative elements are the condensers F, G and H, the rectifying discharge gap J, the line connections, and the reactance K. I

The reactance K may include in its structure a sliding core on an equivalent part of iron or other magnetic material, or, if coreless, may be made variable by other means. When the potential across the condensers F and G Fig. 1, H and G Fig.2 'attains a value which exceeds the potential correspending with the resistance of the dis charge gap J the condensers discharge, the current passing over the gap J. This condenser discharge is very rapid, and tends to oscillate in the exciting circuit. The gap J is adjusted so that at the instant of maximum potential across the condensers, the

latter discharge across the gap at a rate to the radiator at the rate at whichthe radiator can best absorb it. The dimensions of the inductance R are such that it prohibits the flow of the discharge current through it.

If the inductance valve R be adjusted to zero value the charge in the condenser H is released by the discharge across the gap J and in consequence the radiator P becomes energized. When, however, the inductance valve R is adjusted to a higher value, the condenser H is charged by the discharge of the condensers G and H across the gap J, and in consequence, the radiator P becomes energized. The dimensions of the circuit including the transformer secondary E, the inductance K, condensers F, H and G, and the inductance R are such that that portion of the energy stored in the condensers and not absorbed by the radiator but reserved in charge by the single discharge of the condensers is returned to the primary source of power via the transformer E C, that is to say, that the rate of flow of current in this circuitmust agree with the rate of flowof current in the primary circuit A B C I); briefly the circuit E K F R G is in resonance with the current in the circuit A B G D.

Fig. 3 illustrates a form of spark gap of the air cooled type which is effective for the purposes of this invention. The electrodes L and M of the discharge gap J are arranged in series with the condensers F, G, and H. The electrode L is a blunt nosed cone of metal of high electrical conductivity pierced axially with a hole about one sixtyfourth inch diameter and connected by a tube N of an insulating material with a pump or pressure reservoir 0 from which air or gas under high pressure is supplied and blown through said axial hole. The electrode M is a surface of metal of high conductivity mounted in front of the nozzle L and separated therefrom by a distance of about five sixteenths of an inch more or less. One such discharge gap is suflicient for a transmitter supplied with primary energy of 5 kilowatts. In practice the pump or reservoir 0 delivers air mider a pressure of 100 to 105 pounds per square-inch at the nozzles, but pressures up to 500 pounds per square inch may be employed. Only'certain approximate pressures within the range required are usable intermediate pressures producing undesirable effects. The volume of air or gas employed is that necessary to maintain the electrodes at a constant low temperature, while the velocity which is governed by pressure must be sufiicient to remove the ionized air particles upon formation. The sparking distance, volume, and velocity of air must be adjusted until such a combination is reached that only one half of each complete cycle is permitted to dis-' charge across the gap.

signed to radiate a In one practical embodiment of my in vention, the reactance K contains about 24 turns of copper tubing forming a coil of about twelve inches diameter, and, when of the core type, is arranged so as to be slidable longitudinally over a squirrel cage core composed of about 180 pieces of soft iron wire 22 B. W. G. about 211} inches long, the ends of said wires being mounted in end disks and when necessary supported on intermediate spacers.

The inductance valve R is a variable inductance constructed of two pancake spirals S and S arranged foldably bookwise at either side of a slidably withdrawable plate of magnetic material which constitutes a magnetic core. This core comprises a pack of about ten sheets each of 7 millimeter thickness of silicon steel insulated from each other by paper sheets; its area is approximately the area circumscribed by the coils. Each pancake is a heavily insulated spiral coil of 16 B. W. G. wire having about 16 turns, and an external diameter of about 15 inches preferably wound in the same direction. The mechanical form of this inductance valve is not essential to its successful operation, but it is practically necessary that it shall have a core of iron or light magnetic material, and that its inductance "alue shall be adjustable by alteration of the relative positions of the core and coils. This valve is adjusted to pass the charging current stantial impedance; it is shunted around the common condenser and therefore acts to discharge the potential at either side of that condenser without affecting the charge in through it without sub-' the other condensers in the exciting circuit,

and therefore insures a condition of zero potential at the terminals of the radiator while permittin the exciting circuit to become charged. B fects, however, this valve operates during the period of discharge to choke back the high frequency energy currents from the condensers with the result that the current is thrown throu h the common condenser and the radiator liy which it is emitted as an oscillation and is prevented from oscillating in the shunt and so discharging the radiator. This inductance valve therefore functions as a device which inhibits precharging of the radiator but insures the isolation of the upper and lower sections ofthe radiator at the moment of-discharge.

As a practical instance of a transmitter constructed according to my invention deout 1?; kilowatts in the radiatin circuit when a primary ener y of about 3 ilowatts is employed an aeria con- I o I capacity of this air wire system 15 approxiy reason of hysteresis efv mately .0024 microfarads and its natural period of oscillation 500,000 per second.

The capacity. of the connecting condenser.

H which -is common to boththe radiator and exciting circuits is .032 microfarads. The capacity of the fixed condenser F is .014 microfarads, and the capacity of the condenser G is the same. In adjusting the circuits the necessary value of the connecting condenser H is first determined; then the capacities of the fixed condensers F and G are adjusted till the charging circuit is in resonance with the primary circuit. The inductance K is then varied till the time value of the discharge determined by the constants of the exciting circuit is about 10% less than the time value of the oscillation of the radiator, which latter is determined by the radiator constant solely. It is essential that the condenser capacity be of the subdivided type more than two condensers being always employed in either arrangement shown in Figs. 1 or 2 respectively. The structure and proportion of the parts in the reactance and inductance valve are the same as hereinbefore particularized.

In operation in the case of either arrangement of condensers in Figs. 1 and 2 the alternator A supplies current to the primary circuit; this circuit is closed intermittently when transmitting signalsby the manual movements of the sending key B. The primary voltage is steppedup in the trans former CE. The induced current in the secondary E of this transformer energizing .the charging circuits which includes the condensers F, G and H, the aerial being connected to earth through the inductance valve R it is not precharged, as during the char ing process said valve ofi'ers a path for current through which the diiference of potential between the upper and lower parts becomes equalized. When the condenser po tential reaches a value determined by the length of discharge gap J the energy stored in the condenser system discharges across the gap and energy is delivered into the radiator through the connecting condenser.

By having the frequency in the exciting circuit adjusted in conformity to the current pulsations in the generator circuit, an increase in efliciency issecured and the avail able energy is thrown into the radiator circuit at the instant when most useful.

WhatI claim as my invention and desire to secure by Letters Patent is:

1. A wireless telegraph transmitter comprising an exciting circuit and a radiator. connected thereto electrostatically and means for maintaining zero potential in'the radiator during charging eriod.

2. In a wireless te egraph transmitter an exciting circuit and a radiator connected thereto electrostatically and a means for' maintaining z ero potential in the radiator during charging period, and for producing.

a single impulsem the exciting circuit during the discharge period at and by each discharge.

3. I11 a wireless telegraph transmitter, a primary circuit containing a fixed frequency generator, an exciting circuit connected to said primary circuit and containing a plurality of condensers, and a radiator connected electrostatically to said exciting circuit through one of said condensers and containing means for maintaining zero potential in the radiator during the charging period, and means for tuning said exciting circuit to the period of said generator.

4. In a wireless telegraph transmitter an exciting circuit containing a plurality of condensers and a radiator connected thereto through one of said condensers, means for maintaining zero potential in the radiator during the charging period, and means for discharging the exciting circuit instantaneously through the radiator.

5. In a Wireless telegraph transmitter an exciting circuit and a radiator connected thereto electrostatically, means for charging the exciting circuit at fixed regular periods, means for producing aslngle discharge 1n said exciting circuit for each charging pe-.

riod, the electrical constants of said exciting circuit being so adjusted as to render its natural period equal to that of the charging means, and means for maintaining the radiator at zero potential during the charging period.

6. In a wireless telegraph transmitter.

the combination with a power source, an ex-- citing circuit, and a radiator, said power source-having a fixed frequency, of means for tuning the periodof sa1d exciting circuit to the generator frequency, and means for preventing the return of energy from theradiator to the exciting circuit.

7 In a wireless telegraph transmitter an exciting circuit containing a plurality of condensers in series and a radiator connected thereto electrostatically through one of said condensers, the capacity of which condenser is greater than the capacity of the other condensers, means for charging said exciting circuit, and means for dis charging same through the radiator, and

for rendering it passive in relation to the mg said exciting circuit through the radiator intermittently, and for rendering it passive in relation to the radiator frequency during the periods of discharge, and means for maintaining the radiator at zero potential during the charging periods.

9. A Wireless telegraph transmitter comprising an exciting circuit containing a plurality of condensers, a radiator connected thereto electrostatically through one of said condensers, means for charging the exciting circuit at fixed regular periods, means for alternately establishing in said condensers a charged condition in syntony with the frequency of the charging current and a passive condition in relation to the radiator frequency, the natural period of, said exciting circuit being equal to the charging period, means operating during said passive condition for discharging the exciting circuit through-the radiator, and means for maintaining the radiator at zero potential during the charging period.

10. In a wireless telegraph transmitter the combination of an exciting circuit comprising three 01- more condensers, a magnetic material core reactance, and a rectifying discharge gap in series, a radiator including one of such said condensers and a magnetic material core induction valve shunted around said common condenser. Y

11. In a wireless telegraph transmitter comprising an exciting circuit and a radiator, said exciting circuit having three condensers in series, a radiator connected to one of said condensers, a shunt around said last condenser, and means operative simultaneously for producing intermittently interrupting reactances in said exciting circuit and in said shunt.

12. In a Wireless telegraph transmitter, an exciting circuit containing capacity and inductance, a radiating circuit electrostatically connected to said exciting circuit, a unidirectional, arcless spark-gap bridging said exciting circuit, a charging circuit inductively coupled to said exciting circuit, and means for impressing harmonic electromotive force upon said charging circuit at a frequency corresponding to the frequency in said exciting circuit When the Spark gap is inactive.

18. In a wireless telegraph transmitter, an exciting circuit containing capacity and inductance, a transformer secondary comprising a part of said exciting circuit, an arcless, unidirectional spark gap bridging said exciting circuit and arranged as a shunt past said transformer, a radiator electrostatically connected to said exciting circuit, a charging circuit connected to the primary of said, transformer, and means for impressing upon said primary circuit an alternating electromotive force Whose frequency is substantially equal to'the frequency of said'exciting circuitiwhen thespark gap is inactive.

14. In a Wireless telegraph transmitter, an exciting circuit containing capacity and inductance, a transformer secondary comprising a part of a said exciting circuit, an arcless, unidirectional spark gap bridging said exciting circuit and arranged as a shunt past said transformer, a radiator inductively connected to said exciting circuit, a charging circuit connected to the primary of ,said

transformer, means for impressing upon said primary circuit an alternating electromotive'force, and means for tuning said ex-. citing circuit to the alternations of said alternating electromotive force.

In testiniony whereof I have affixed my signature in presence of two Witnesses.

JOHN GROEM'E BALSILLIE.

Witnesses ()HARLES HARKELL, LUCY GREEN. 

